This invention relates to pneumatic outlets for use in unloading hopper type containers, including but not limited to railway hopper cars. One currently used technique for unloading such hoppers is the so-called "tube within a tube" or "valve within a tube". Description of the construction of these respective pneumatic outlets is found respectively in U.S. Pat. Nos. 3,194,420 and 3,778,114. The latter concept, the valve within a tube, has the advantage that usually the outlet does not have to be disassembled in switching from one lading to another.
However, in both of these constructions the product hose between the hopper outlet and the container into which the lading is being unloaded must deflect angularly during adjustment of the valve during unloading. A rather high operating torque on the part of the operator is required to make these adjustments. The problem has been found to be more acute during cold weather when the metal parts have contracted somewhat.
A second problem which has been encountered with the tube within a tube and the valve within a tube outlets has been the operation of the outlet after the outlet has been impacted; for example, in the case of a railway hopper car, if the outlet contacts something in transit on the track or near the track. With the close tolerances required in these constructions, the tube or valve often will not operate at all. Thus the entire outlet must be removed from the hopper to unload the lading. This requires considerable operator time and may hold the container up from use in other services. Thus inoperability of the tube in a tube and valve in a tube due to impact can be expensive.
It is to be borne in mind that current standards in the railway industry require that any pneumatic outlet introduced must be entirely operable from one side of the car. This may also be advantageous in container outlets and in fixed bin installations. This means that the operator must be able to unload first the side opposite to the operating side and then the operating side to avoid short circuiting when an air space occurs in the pneumatic system and thus the lading is no longer conveyed by the pneumatic system. Thus the outlet must have the capability while the operator is standing on any given side of the outlet, of allowing the far side of the outlet to be unloaded first. It will be apparent to those skilled in the art that this requires a translating mechanism for opening the outlet from the opposite side of the outlet while maintaining the near side of the outlet closed.